At present, many types of display device are provided, in which one of the types of the display device is a projection apparatus having a smaller size to be capable of projecting a large size image being a plurality of times over a surface area of the projection apparatus, thereby resulting in the projection apparatus having an irreplaceable superiority in the display industry.
A conventional projection apparatus has a light valve to form a fixed offset relative to an optical axis for projecting an image into the screen. However, the fixed offset of the light valve cannot be changed because the projecting lens is fixed on the projection apparatus. Therefore, once an image projecting location has to be changed, a location of the projection apparatus also has to be changed. In the other words, once the location of the projection apparatus has to be changed, the image projecting location also has to be changed. From another point of view, owing that the conventional projection apparatus cannot change the fixed offset of the light valve of the projecting lens, the conventional projection apparatus may be inconvenient to be used.
Recently, there are some patents about disposing an extra structure to change the location of the projection apparatus for projecting a image onto a target position such as U.S. Pat. No. 6,966,657B2, U.S. Pat. No. 6,829,108B2, U.S. Pat. No. 7,064,910B2, and so on. However, the aforementioned patents still have some problems.
The information disclosed in this BACKGROUND section is only for enhancement of understanding of the BACKGROUND of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the BACKGROUND section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art.